Labor-power is paid its value, which is the cost to reproduce a day of labor. The problem is that workers work beyond the number of hours needed to do so due to capitalist relations. In other words, a worker sells their labor power for 1 day to earn the ability to survive another day, but the capitalist gets out of it more commodities than the worker needed and thus comes the profit, this surplus value creation. Commodities are sold at their value, not above it, to still make a profit.

Huge simplification though, there exists super-exploitation of the global south via imperialism, there's also the reserve army of labor and intentional homelessness to force lower wages, and the struggle for higher wages by workers.

Might need to re-read Capital tho, I've been focusing on DiaMat and hismat and am a bit rusty economically.